1. Field of the Invention
The present invention relates to a seat slide device of a motor vehicle, which device slides a seat to a desired position and locks the same at the desired position. More specifically, the present invention relates to a seat slide device which is equipped with a rail-coupling reinforcing structure for protecting the seat slide device from damage even when the same is applied with an abnormally big shock, due to a vehicle collision or the like.
2. Description of the Prior Art
Most of the seat slide devices hitherto proposed are of a type which comprises two stationary rails mounted on a vehicle floor, two movable rails slidably carried on the stationary rails and mounting thereon a seat, and a position locking mechanism for locking the movable rails at a desired position relative to the stationary rails. For increasing the mechanical strength, some of them are equipped with a so-called "rail-coupling reinforcing structure" which is designed to assure the functional connection between the stationary and movable rails which are coupled. Thus, the seat slide devices equipped with the rail-coupling reinforcing structure can exhibit a considerable resistance against a big shock applied thereto due to a vehicle collision or the like. One of the seat slide devices of this type is disclosed in Japanese Patent First Provisional Publication No. 59-134031.
The rail-coupling reinforcing structure disclosed by the Publication comprises an elongate plate which extends along one of the stationary rails and is secured thereto. The plate has mounting lugs secured to the vehicle floor and has at its upper end a folded-back channel portion which extends therealong. A generally L-shaped holding bracket is secured to the corresponding movable rail and slidably interconnected with an edge of the channel portion of the elongate plate. When, due to a vehicle collision or the like, the movable rail is applied with an abnormally big shock in a direction away from the stationary rail, the L-shaped holding bracket become tightly engaged with the edge of the channel portion thereby suppressing disengagement between the coupled two rails.
However, due to its inherency in construction, the rail-coupling reinforcing structure has caused a bulky and heavy construction of the seat slide device to which the reinforcing structure is practically applied. As is known, the bulky and heavy construction brings about not only poor space saving of the vehicle cabin but also deterioration in fuel consumption of the motor vehicle.